Once again, an alleged advance using embryonic stem cells is being hyped in the media as a major scientific breakthrough, when in fact it merely repeats earlier, and more successful advances using adult stem cells and other alternatives. Moreover, the alleged breakthrough is being hyped at the expense of ignoring or misrepresenting these alternatives.

This time, according to recent news reports, embryonic stem cells have been transformed into endothelial (blood vessel) cells and small blood vessels. Dr. Robert Langer of MIT, is quoted as saying “This is the first time this has been done with human cells” (“Blood Vessels Made From Stem Cells”, AP Online, 03/25/02). Another report says “But to date, adult stem cells have not come close to spontaneously forming blood vessels, as Langer’s embryonic stem cells did.” (“Stem cells converted to functioning blood vessels,” Boston Globe, 3/26/2002).

These assertions are simply wrong, and can only be the result of ignorance of the significant peer-reviewed literature that shows otherwise.

The report may be the first to show that human embryonic stem cells might be able to form blood vessels. However, it IS NOT the first time human stem cells have been used to form blood vessel cells and blood vessels.

Adult stem cells from humans and animals have already shown the ability to stimulate new blood vessel formation, both spontaneously in culture as well as when injected into animals (most recently by a group from the University of Minnesota, M. Reyes et al.; “Origin of endothelial progenitors in human postnatal bone marrow;” Journal of Clinical Investigation 109, 337-346; February 2002). This ability of adult stem cells to participate in the formation of new blood vessels has been known for several years. Furthermore, the new embryonic stem cell study is even behind what is now being done in human patients using no new cells at all, but only the injection of growth factors and gene therapy that stimulates growth of new blood vessels by the body itself, to restore circulation to the heart and limbs.